1. Field
Exemplary embodiments relate to a resolution improvement of various display devices, and more particularly, to an image resolution improvement apparatus that may overcome a blur phenomenon of a high frequency area of an image, and to a method of operating the same.
2. Description of the Related Art
In general, since realism and immersion for a viewer increases as display apparatuses become larger, display apparatuses, having a large size and a high-resolution, are being rapidly developed. In particular, a development in a plane panel TV such as a plasma display panel (PDP) and a liquid crystal display (LCD) may accelerate the above described development in display apparatuses. Nevertheless, a development in acquisition and generation of image content may not keep pace with the development of the display apparatuses. Thus, a resolution improvement of a low resolution to a high resolution or of the low resolution to an ultra high-resolution may need to be included. However, an existing linear interpolation-based scaler may have disadvantages in that a definition is deteriorated and a blur phenomenon is generated due to a failure in compensating for a shortage of high frequency elements.
To improve a resolution using a single input image, a resolution improvement may need to be performed while including as much information capable of being extracted from the input image as possible. A generally used ultra-high resolution improvement algorithm may be an Iterative Back Projection (IBP) algorithm.
The IBP algorithm may perform five operations. First, the IBP algorithm may convert an input image inputted in a low resolution into an initial high resolution image. Second, the IBP algorithm may reduce the high resolution image into a low resolution image having the same resolution as in the input image. Third, the IBP algorithm may calculate a difference between the input image and the reduced image to generate a differential image. Fourth, the IBP algorithm may expand the differential image into a high resolution, and generate a high resolution image in addition to a currently generated high resolution image. Fifth, the IBP algorithm may iteratively perform the second to fourth operations a predetermined number of times.
The above described iteration algorithm may generate the high resolution image having an improved definition by continuously updating information of the input image through an iteration operation. That is, the high resolution image may be corrected through an update operation using a difference between an image generated in the high resolution image and the input image, thereby generating the high resolution image having the improved definition.
That is, as the operation is iteratively performed, an updated differential image may correspond to a high frequency element obtained such that the low frequency element is gradually removed from the input image. The high frequency element in which the low frequency element is removed from the input image may be repeatedly updated in the high resolution image, thereby obtaining the high resolution image having the improved definition.
The iteration algorithm may be expressed asIt+1h=Ith+EXPAND(Il−REDUCE(Ith)).  [Equation 1]
where Il denotes a low resolution-input image, Ih denotes a high resolution image, t denotes an iteration, EXPAND( ) denotes a function expanding from the low resolution image to the high resolution image, and REDUCE( ) denotes a function reducing from the high resolution image to the low resolution image.
An element practically updated in Equation 1 may correspond to Il−REDUCE(Ith), and REDUCE(Ith) may correspond to a low frequency element of the input image. Accordingly, the updated element may correspond to a high frequency element of the input image. That is, since the high frequency element of the input image is updated, a subsequent differential image may correspond to the high frequency element in which the low frequency element is more greatly removed from the input image in comparison with a preceding differential image. Also, the subsequent differential image may correspond to the high frequency element of which a magnitude is reduced.